/*
 * Copyright (c) 2001, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 */

package com.sun.imageio.plugins.jpeg;

import javax.imageio.metadata.IIOMetadataNode;
import javax.imageio.stream.ImageOutputStream;
import javax.imageio.metadata.IIOInvalidTreeException;

import java.io.IOException;
import java.io.UnsupportedEncodingException;

import org.w3c.dom.Node;

/**
 * A Comment marker segment.  Retains an array of bytes representing the
 * comment data as it is read from the stream.  If the marker segment is
 * constructed from a String, then local default encoding is assumed
 * when creating the byte array.  If the marker segment is created from
 * an <code>IIOMetadataNode</code>, the user object, if present is
 * assumed to be a byte array containing the comment data.  If there is
 * no user object then the comment attribute is used to create the
 * byte array, again assuming the default local encoding.
 */
class COMMarkerSegment extends MarkerSegment {

  private static final String ENCODING = "ISO-8859-1";

  /**
   * Constructs a marker segment from the given buffer, which contains
   * data from an <code>ImageInputStream</code>.  This is used when
   * reading metadata from a stream.
   */
  COMMarkerSegment(JPEGBuffer buffer) throws IOException {
    super(buffer);
    loadData(buffer);
  }

  /**
   * Constructs a marker segment from a String.  This is used when
   * modifying metadata from a non-native tree and when transcoding.
   * The default encoding is used to construct the byte array.
   */
  COMMarkerSegment(String comment) {
    super(JPEG.COM);
    data = comment.getBytes(); // Default encoding
  }

  /**
   * Constructs a marker segment from a native tree node.  If the node
   * is an <code>IIOMetadataNode</code> and contains a user object,
   * that object is used rather than the string attribute.  If the
   * string attribute is used, the default encoding is used.
   */
  COMMarkerSegment(Node node) throws IIOInvalidTreeException {
    super(JPEG.COM);
    if (node instanceof IIOMetadataNode) {
      IIOMetadataNode ourNode = (IIOMetadataNode) node;
      data = (byte[]) ourNode.getUserObject();
    }
    if (data == null) {
      String comment =
          node.getAttributes().getNamedItem("comment").getNodeValue();
      if (comment != null) {
        data = comment.getBytes(); // Default encoding
      } else {
        throw new IIOInvalidTreeException("Empty comment node!", node);
      }
    }
  }

  /**
   * Returns the array encoded as a String, using ISO-Latin-1 encoding.
   * If an application needs another encoding, the data array must be
   * consulted directly.
   */
  String getComment() {
    try {
      return new String(data, ENCODING);
    } catch (UnsupportedEncodingException e) {
    }  // Won't happen
    return null;
  }

  /**
   * Returns an <code>IIOMetadataNode</code> containing the data array
   * as a user object and a string encoded using ISO-8895-1, as an
   * attribute.
   */
  IIOMetadataNode getNativeNode() {
    IIOMetadataNode node = new IIOMetadataNode("com");
    node.setAttribute("comment", getComment());
    if (data != null) {
      node.setUserObject(data.clone());
    }
    return node;
  }

  /**
   * Writes the data for this segment to the stream in
   * valid JPEG format, directly from the data array.
   */
  void write(ImageOutputStream ios) throws IOException {
    length = 2 + data.length;
    writeTag(ios);
    ios.write(data);
  }

  void print() {
    printTag("COM");
    System.out.println("<" + getComment() + ">");
  }
}
